The present invention relates generally to fluid seals, and more particularly to seals adapted for use in high pressure environments, particularly those involving reciprocating or sliding motion of a sealed part axially through the seal opening.
While hydraulic pressure actuated mechanisms are becoming increasingly more common, and operate on familiar principles, recent applications of certain hydraulic mechanisms, such as automotive power steering units, for example, are often subject to operational conditions so severe as to tax prior known seal designs. For example, where mechanisms are becoming more compact and light weight, but still require application of substantially the same operating forces, certain parts of the sealed hydraulic mechanisms are exposed to increasingly higher pressures.
Other known mechanisms which are required to be operated at pressures of a given level are being subjected to more severe conditions by reason of increased rates or ranges of movements. These applications include rods and the like sealed by so called rod wiper type radial lip shaft seals. In these applications, the rod moves axially through an opening in the seal and the lip portion of the seal is exposed to fluid under pressure sometimes reaching or exceeding several hundred to over one thousand (1,000) pounds per square inch.
These applications can occasion severe wear in the seals themselves, in the sealed parts if there is insufficient lubrication, or leakage if there is insufficiently tight sealing in the sealed area. Every lubricated mechanism, including hydraulic mechanisms, is subject to catastrophic failure when leakage is such that the supply of lubricant or operating fluid is completely depleted.
Under the circumstances, there is a need for seals which undergo reduced wear and drag in respect to prior art seals, without suffering loss of sealing effectiveness.
According to the invention, an improved radial lip seal is provided which includes a lip portion having air and oil sides forming a seal lip body bonded to a radially inner portion of a seal casing, and wherein the so called air side of the seal lip is contoured so as to provide, in combination, a multi-lip sealing surface, controlled deflection under pressure, and excellent lubricant retention to provide improved performance in many applications.
In view of the failure of the prior art to provide seals capable of functioning at top performance levels in certain demanding environments, it is an object of the present invention to provide an improved high pressure fluid seal.
Another object of the invention is to provide a fluid seal having a contoured sealing lip adapted for use in high pressure environments.
Another object of the invention is to provide a fluid lip seal having a casing portion and a sealing lip body with relatively conventional oil side frustoconical lip surface meeting an air side surface which is contoured so as to provide plural sealing lips or ribs and annular, lubricant-retaining grooves therebetween
Yet another object of the invention is to provide a high pressure radial shaft lip seal which includes a primary lip seal body having a primary seal band, a seal formed by the meeting of air and oil side frustoconical primary lip surfaces, and a plurality of auxiliary sealing ribs each separated from an adjacent rib by a circumferential groove, with the ribs having progressively increasing inside diameters so as to provide a sequential contact response on an associated shaft with an increase in pressure, to provide a gradually increasing seal "footprint" on the sealed shaft in the presence of increasing hydraulic pressures.
A still further object of the invention is to provide a high pressure seal having a primary seal lip and several auxiliary lips each adapted to engage a sealed part such as a reciprocable rod, and which further includes means for retaining fluid between such auxiliary lips for additional lubrication and reduced wear.
A still further object of the invention is to provide a composite elastomeric and metal seal which is adapted to provide reduced seal and sealed part wear in use.
Another object of the invention is to provide a seal which is capable of being used with or without auxiliary seal elements and which will assume in use an on-shaft profile adapted to reduce wear, retain lubricant, and reduce drag in use without sacrifice of sealing ability.
A still further object of the invention is to provide a seal which undergoes a gradual change of "barrel angle" in use as it encounters varying pressures in a sealed application.
The foregoing other objects are achieved in practice by providing a fluid seal having a seal casing and an elastomeric lip body bonded thereto, with the lip body being of annular form and including a frustoconical oil side surface meeting a frustoconical air side surface along a substantially circular, circumferentially extending seal band, and having its frustoconical air side surface further including a series of axially spaced apart ribs of smooth contour and gradually increasing inner diameters, spaced from each other by lubricant-retaining grooves, with the entire seal body being adapted to be urged into snug sealing engagement with an associated shaft by progressively increasing contact of said ribs with the sealed reciprocable shaft as the pressure in the sealed region increases.
The manner in which these and other objects and advantages to the invention are achieved in practice will become more clearly apparent when reference is made to the following detailed description of the invention set forth by way of example and shown in the accompanying drawings wherein like reference numbers indicate corresponding parts throughout.